Instability
Over the years SHGC members have suffered many serious accidents. A common failing seems to be that of failing to allow the glider to resume normal flight after an event.
Most gliders that are in trim and not overly permeable ('porous') will resume normal flight from a stalled or spinning configuration by simply releasing the brakes; it is very rare that the pilot benefits from continuing to hold the glider back after the initial event has recovered until they hit the ground (Piloting the wreckage to the scene of the crash...)
Distilling years of training, flying and SIV courses into a few simple rules, this being no substitute for training and currency:
1. If in any doubt, deploy your reserve. Never think that you are too low to deploy. Repack your reserve every three months to ensure it will open as quickly as possible. Learn to do it yourself!
2. If the glider front collapses through 50% or less, use weight shift and a minimum of brake to maintain a safe course. If you have brake applied when the wing collapses, do not release it as you will initiate a dive.
3. If the glider front collapses through greater than 50%, allow the initial surge to proceed, releasing brake if already applied, then once it has surged as far as it will, counter the turn/dive using brake to perform a controlled swoop under the wing, during which most of the wing should re-inflate and the remaining deflation may be treated as per 2 above.
4. If the glider suffers a full frontal deflation, especially if it is EN-C or above, immediately pump both brakes as fast and fully as you can and immediately release them fully. Only catch the recovery surge if it goes beyond 30 degrees or so. Do not stall the wing. Watch https://youtu.be/YI_x9nSgs68
5. If the glider spins, immediately release the initiating brake. Only release the other brake if the wing doesn't immediately recover.
6. Practice slow flight while very close to the ground (<1m) when slope landing. Do not practise slow flight when top landing while several metres above the ground.
7. Learn to recognise and recover deep stall while ground handling.
8. Cravattes - The simplest procedure for managing cravattes is to pull a big ear, a two line big ear or a 50% deflation to incorporate and thus negate the cravat. Pilots of higher aspect ratio wings may also use the Enleau technique, but this isn't a universal fix.
9. Inadvertent spiral dives - Pull both brakes to slow the dive then weight shift and steer out of the spiral. This should result in a powerful pitch back and climb. At this juncture put the brakes all the way up and look up for the wing. At the top of the climb, modern wings surge aggressively. Allow the surge to proceed to about 30 degrees then stop the dive with a brief application of the brakes then immediately release all brake to allow the glider to regain flying speed.
10. Watch Instability 2 until you can recite Bruce's dulcet tones backwards whilst sat inside the washing machine on a spin cycle. Use self visualisation techniques to help reinforce those words.